In trainings of sportsmen, mainly in bodybuilding and power-lifting, there is often a requirement of smooth increase in loading either in a positive, or in a negative movement phases.
Adaptations for an increase of the load in the negative phase are unknown. For getting this effect in trainings, a sportsman usually uses the help of a partner putting additional pressure upon a basic burden.
For increasing the load in the positive phase one usually uses metal chains secured on the basic burden. Thusly, the weight of the chains creates an additional burden thereby increasing the load for muscles of the sportsman. In the process of lowering the basic burden, the chain's links lay down on the floor, and the weight of additional burden decreases. In the process of lifting the basic burden, the chain links get off the floor, increasing the weight of additional burden.
The above described method has the following shortcoming: for athletes of different levels of preparation, it is necessary to use chains of different weights. It demands the presence of a considerable quantity of chains, creates difficulties in their storage and moving in an exercise room.